Saving variable value to a file does not work!!!!

[John Roth]

"Gerhard Häring" <gh_pythonlist at gmx.de> wrote in message
news:mailman.1001867134.25402.python-list at python.org...
> On Sun, Sep 30, 2001 at 06:04:33PM +0200, Husam wrote:
> > Hi friends,
> > Im  a newbie and trying to save the value of variable 'counter' to a
> > file, but it does not work.
> > The code Im usig is:
> >
> >
> > for line in lines:                # I'm reading from file: test2.txt.
> > One of it's lines contain: ID 5.
> >     string.split(line)
> >     if line[0:2]=='ID':
> >         counter=int(line[3])
> >         output=open('test2.txt','a') # Hier Im opening the same file for
> > append.
> >         output.write(counter +1)            # This is the trouble making
> > line!
> > output.close()
>
> Btw. the string.split(line) doesn't do anything in your case, if you
> want to store the output of the split function, you can use something
> like "mylist = string.split(line)". But now the the real problem.
>
> > The error message I get when this code is run:
> >
> > Traceback (innermost last):
> >   File "./script.py", line 23, in ?
> >     output.write(counter+1)
> > TypeError: read-only buffer, int
>
> You can't write any ints with the write function. But you can write
> strings. Just do
>
>     output.write(str(counter + 1))
>
> I acknowledge this is a bit strange. And I also don't know the reason
> why the conversion to string doesn't happen automatically, like with the
> print statement.

Print is for formatted output that is intended to be read by people
(usually programmers.) Write is for output that is intended to be read back
by a program.

When you're writing to a file, you want to be able to read it back, right?
If the system converted integers to strings, then you would need to put
delimiters and all sorts of other stuff onto the file to be able to parse it
when you read it. That's what Basic did, and anybody who works in
that language can tell you exactly how ugly it gets.

I'd much rather have the virtue of simplicity - what's on disk is exactly
what I have in memory. Period. When I write a line, I want it read back
the same way, and if that means that all I can write is strings, then so be
it.

>
> Gerhard
> --
> mail:   gerhard <at> bigfoot <dot> de       registered Linux user #64239
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> reduce(lambda x,y:x+y,map(lambda
x:chr(ord(x)^42),tuple('zS^BED\nX_FOY\x0b')))
>